This application is in response to the program announcement entitled, "International Research Collaboration on Drug Addiction" (PA-06050). We propose to conduct longitudinal observational studies in two countries - India and Vietnam - each with significant problems of drug abuse and increasing incidence of HIV. In both countries the HIV epidemic is rapidly emerging as a direct result of injection drug use. Furthermore, the governments of both countries have recently initiated programs to provide combination antiretroviral therapy to HIV-infected patients. An important goal of this proposal is to initiate research in these countries to establish baseline nutrition and metabolic status of HIV-infected patients prior to widespread access to HAART and to follow participants who start on a first-line HAART regimen to document the natural history of treated HIV infection in these countries. This is an important window of opportunity to conduct the proposed studies as, over time, access to patients who are HAART-naive may be diminished and regimens will become more complicated. Our specific aims are as follows: 1) To characterize and compare HIV-negative and HIV-positive (HAART and non-HAART) injecting drug users (IDUs) in terms of: a) types, frequency and patterns of illicit drug use, b) co-morbidities, c) nutritional and metabolic abnormalities, and d) clinical outcomes;2) To examine the independent contributions of adherence to HIV medications, psychosocial factors (e.g. depression), and socioeconomic factors (e.g. food insecurity) to the development or persistence of nutritional and metabolic abnormalities;and 3) To establish an infrastructure and ongoing presence in these countries so that with the increasing availability of interventions for HIV, we will have populations on which to build future studies. Results from these international studies will not only provide important data for HIV-infected patients within these countries, but will also serve as comparisons for U.S. based studies. Comparison of findings between U.S. and international studies will help expand our understanding of the causes and consequences of metabolic complications in chronic HIV infection in the U.S. Furthermore, the results of this project will help to identify generalized malnutrition or specific micronutrient deficiencies in the local populations that may be amenable to nutritional interventions for delaying HIV disease progression. These might include vitamin supplementation and/or dietary counseling to improve the quality of food intake.